Thyroxine is an important hormone released into the bloodstream by the thyroid gland in the body. When tyroxine is released into the blood stream, it moves through certain organs such as the kidney and liver, where most of it is changed to an active form known as triiodothyronine. Thyroxine perform important roles in brain development, heart and digestive functions, bone maintenance, controlling muscle and metabolic rate of the body.
 
        
             
        
        
        
Answer:
D. antigen only come from microbes
Explanation:
Antigens are substances which elicits a response by the antibodies. Antigens Antigens include proteins, nucleic acids, lipoproteins, glycoproteins, and certain large polysaccharides. 
They parts of antigen molecules that initiate immune responses are called epitopes or antigenic determinants. 
 
        
                    
             
        
        
        
Answer:
They release C02, which contributes to climate change.
They can cause health issues.
Explanation:
The other two are positive aspects, and these two are true.